Q&A: Weather Balloons Revisited

Question: I was reading one your older columns, about how Venus gets reported as a UFO, and got me thinking about this bright object I saw a couple months back, only this one was moving, so it couldn’t be Venus. And it was much brighter than Venus, and didn’t have blinking lights like an airplane. Do you think I saw a UFO? — JC, New River, AZ

Answer: If you couldn’t identify what it was, and if it was flying, then, by definition, it was a “UFO” (unidentified flying object). But I’m pretty sure I can identify what you saw that night (making it an IFO). What you saw was probably just a weather balloon.

The National Weather Service (NWS) launches these balloons from several locations. They’re made from a Mylar-like material that is very highly reflective, like a mirror. Under the right conditions, usually just after sunset or before dawn, they are so high up (100,000 feet or more) that sunlight illuminates them, and that makes them look very bright indeed. When you watch the sky as much as I do, you see these things every few months. NWS uses these balloons them to help them make accurate weather forecasts.

The photo above was taken by local amateur astronomer Chris Schur, near Payson, AZ, using a Canon 10D with a 400 mm telephoto lens. The inset shows a further enlarged view, as well as the balloon payload (measuring instruments) suspended below. By the color of the sky, you can tell that it’s still not totally dark. These balloons get so bright that you’ll actually see them in twilight or dawn. See more of Chris’ (and wife Dawn’s) amazing astrophotos on their website at: www.schursastrophotography.com.

Note: This is a repeat on the topic of weather balloons, but I get asked about this often. Also, the March 8, 2008 column was back in the grayscale era of Sky Lights, and now I can use the color version. Take a look at that older column if you want to understand better how the Sun can light up these balloons.